Deese's Donut is located on Shires Drive, you firstly need to drive up to the top of the car park on the left side of the road when coming off the bridge (Go up 3 floors).
Once you have reached the open top of the car park go up the large ramp in front of you to get atop the next roof and drive to the end and turn around to face a split ramp. (You will be able to see the top of the donut from here)
Id suggest avoid doing a barrel roll here and once you land the jump through the hole in the middle of the massive donut and the trophy is yours.
Here's a video